Pneumatic tool holding and operating device



Patented Apr. 21,1891.

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liTn STnTns PATnNT GFFICE.

FRANZ .IAKOB LAUN, OF VILLINGEN, GERMANY.

PNEUIVIATIC TOOL. HOLDING AND OPERATING DEVICE.

:EBPECIFICATION forming part of Letters Patent No. 450,782, dated April 21, 1891.

Application filed November 7,1890. Serial Nol 370,704. (No modell) To @ZZ whom, t may concern:

Be it known that I, FRANZ J AKOB LAUN, a subject of the Grand Duke of Baden, German Empire7 residing at Villingen, Baden, Germany, have invented a new and useful Pneumatic Tool Holding and Operating Device, of which the following is a full, clear, and exact description.

My invention has for its object to improve that class of pneumatic tool holding and operating devices usually used as dental pluggers by causing the tool-carryin g part to move more and more quietly and easily and without the violent vibrations which are frequently experienced in using tools of this kind as now usually constructed, and, further, to prevent uneven or one-sided wear of the moving parts.

To secure the first of these objects I connect with the tool-carrying part of the device a piston independent of the driving-piston and arrange certain air ducts or passages so that this part after being drawn forward by the driving-piston is moved back or raised by the compressed air or other motor-fluid which operates the device, and also so arrange the parts of the device that the tool-carrying holder or stem is moved a greater distance than is the piston which draws it.

To secure the second object of the invention I arrange in a novel manner the reversing channels or grooves, whereby the compressed air 0r other motor-fluid may Operate simultaneously in a uniform manner on two opposite sides of the driving-piston.

The invention therefore consists in the improved combination, construction, and arrangements of the parts of the tool-holder, as will be hereinafter pointed out.

In the annexed drawings, which form part of this specification, Figures I, II, and III show longitudinal sections of the new apparatus in different periods of action, the piston A in Fig. II being at a right angle to its position in Figs. I and III. Figs. IV and V show details of the apparatus, and Fig. VI shows a modified construction.

In a chamber B, which is at rightangles to the axis of the driving-piston A,worlrs the piston-valve B, alternately opening and closing in the known manner the channels a c for the fresh compressed air andthe channels b b2 for the exhaust-air, such channels being arranged within the piston A. Then the piston has assumed its lowest position, Fig. I, the fresh air will pass through the small pipe C, channel a, the part I of the chamber B', and channel a directly and indirectly bythe way of the branch channel c c under the driving-piston A. From here the compressed air will pass through the cent-ral groove d and a groove d', placed at right angles to the same in the tool-holder D under the piston-head E, arranged on this holder. The'compressed air will now raise the small piston E, with the tool-holder D and the driving-piston A, so far that it can Iiow off through the exhaust-channel ein the wall F of the apparatus. In this ascending movement the tool-holder will be stopped before the driving-piston A, which will still continue, and thus assume its highest position, Fig. III. The tool-holder D is stopped by the conducting-ring O, which encircles the piston E and in which the latter has a limited sliding movement, coming in contact with a shoulder n, formed on the inside of the wall of the casing. The air above the driving-piston will iiow during the rise of the piston through the channel b3, arranged through the upper part of the piston A, into the portion 1l of the chamber B', thence through channel b into the cavity f', and subsequently into the groove f2, Fig. IV, from whence it is discharged through the channel f3 and the exhaust-groove g, Fig. Il, arranged in the wall F of the apparatus. It will be seen that the two cavities l and 2 in the casing-wall F are arranged opposite one end of the chamber B for the reversing-piston, and that the cavity 3 is in the diametrically-opposite wall of the casing opposite the other end of the chamber. As soon as the driving-piston has reached its highest position the fresh compressed air liows from channel a, by the way of the small groove It in the piston A and the cavity l in the Wall of the casing, against the piston-valve B and pushes it to the right, whereby the air on the other side of this piston will be discharged, by way of the cavity 3 in the casing-wall and the small passage h-'r in the piston, into the groove f, and thence through the channels f2 f3 and the ex- IOO liaust-port g. Consequently the piston has been reversed-that is, the fresh compressed air Will now enter through channel CL into the portion ll of the chamber B', and thence through channel b3 to the top of the drivingpiston A. This piston is noW pushed downward, and thus imparts a blow to the toolholder D. The air under the piston will first oW off into the dischargefopenings e; but as soon as this opening is cut off by the piston E it will go back through the channels d CZ, c, and a to the portion 1 of the chamber B', and thence it is discharged through channel b2 into the cavity f and by means of the grooves f 2 and f3 and the exhaust-channel g. In the meantime the tool-holder D is thrown forward, and in consequence of its shortened head-piece it `goes a little farther than the piston A, the stroke of which is ended earlier. This larger stroke of the tool-holderprevents a too violent bloW of the tool on the matter which is operated upon, and the operator will not experience a vibration of any importance, so that he is enabled to conduct the apparatus with the greatest accuracy. The reversal of the piston B at the lowest position of the piston A is caused by the fresh compressed air flowing through channel 7L, Fig. I, and cavity 3 behind the piston-valve B, which is consequently pushed to the left, Fig. I. The air at the left side of the piston-valve is then driven out, by Way of the cavity 2, channel h3, and cavity f into the groove f2, and thence discharged through groove f3 and exhaust g, Fig. II.

ln the arrangement shown in FigzVI the nnder part of the apparatus and the tool-holder are modified in such a manner that a considerably simplified construction is obtained. The conducting-ring O, encircling the piston E of thc tool-holder D, is removed and substituted by an annular interior rim M of the under part of the apparatus. The piston E of the tool-holder is solid, and the passage m is made in the above-mentioned interior ring, so that the compressed air can flow under the piston E and raise it together with the toolholder. If the latter has been raised so far that the discharge-opening e becomes free, the air will be discharged through it.

In order to prevent the tool-holder from being raised too high, I have arranged a ring ne on the piston-rod under the apparatus.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is-

l. In a pneumatic tool holder and operating device, the combination of the driving-piston, the tool holder or carriage, the piston connected therewith, and the conducting-passages for the motor-Huid leading below the last said piston and the discharge-passage leading therefrom, substantially as set forth.

2. In a pneumatic tool holder and operating device, the combination of the hollow casing having the cavities l, 2, and 3 in the inner Walls thereof, the cavities 1 and 2 being opposite the cavity 3, the driving-piston Working in the said casing and having the chamber B', the reversing-piston in the said chamber, the channels a, b', b2, and b3, arranged, as described, within the driving-piston, and suitable eXhaust-channels, substantially as set forth.

In witness whereof I have hereunto set my hand in presence of two Witnesses. l

FRANZ JAKOB LAUN.

Witnesses:

CARL ALBERS, EMIL SCHNEIDER. 

